Hereinafter, a description will be given of a spectrophotometer as a conventional chromatography quantitative measuring apparatus. FIG. 25(a) is a diagram schematically illustrating the configuration of the conventional reflective spectrophotometer, and FIG. 25(b) is a diagram illustrating the constitution of a chromatography test strip.
In FIG. 25(a), an optical beam 11 emitted from a lamp 1 is input to a diffraction grating 3 via a reflector 2. The optical beam 11 input to the diffraction grating 3 is selected thereby for its light wavelength, and the optical beam 11 is narrowed by an aperture 4 and input to a glass plate 5. The optical beam 11 reflected at the glass plate 5 is received by a first photomultiplier tube 7 as a reference beam 6. On the other hand, the optical beam 11 transmitted through the glass plate 5 is applied to a part of a chromatography test strip 8, and a scattering light 9 from the chromatography test strip 8 is received by a second photomultiplier tube 10. Output signals from the first photomultiplier tube 7 and the second photomultiplier tube 10 are respectively subjected to Log transformation, and a value obtained by subtracting a Log transformed value for the second photomultiplier tube 10 from a Log transformed value for the first photomultiplier tube 7 is output as an absorbance signal.
As shown in FIG. 25(b), the immuno-chromatography test strip 8 utilizing an antigen antibody reaction comprises an application part 81 where a liquid sample as an inspection target solution is applied, a marker reagent hold part 82 which holds a marker reagent which is moved by permeation of the liquid sample and has a substance that is specifically bounded to an analysis target included in the liquid which flows therein, a detection part 83 where the marker reagent and the analysis target are bounded and immobilized, a part for absorbing the sample which flows therein, and a remaining base part 84.
An operation of the so-configured chromatography quantitative measuring apparatus will be described.
First, when an inspection target solution is applied to the application part 81, the inspection target solution is developed on a development layer 85. At this time, when the inspection target solution reaches the marker reagent hold part 82, a marker reagent is eluted and specifically bonded to an analysis target included in the inspection target solution. Then, this bounded material is immobilized at the detection part 83, and a non-immobilized residual marker reagent flows downstream of the development layer 85 without being immobilized.
Next, as shown in FIG. 25(a), a beam is applied to the chromatography test strip 8 from the light source 1 so as to measure the concentration of the analysis target included in the inspection target solution. A previously-calculated calibration curve indicates a relationship between the difference between the absorbance signal at the base part 84 of the chromatography test strip 8 and the absorbance signal at the detection part 83, and the concentration of a sample to be measured. The concentration of the sample is calculated by detecting the difference between the absorbance signal at the base part 84 and that at the detection part 83.
While analysis by immuno-chromatography is generally qualitative, a method of quantitative analysis has also been developed. For example, Japanese Published Patent Application No. Hei. 8-240591 discloses a method by which the degree of coloration is quantitatively measured by measuring signals of absorbance, reflection, and the like at a coloration part on a test strip employing a spectrophotometer after a sample is applied to the immuno-chromatography test strip and a reaction is caused thereon. Further, Japanese Published Patent Application No. Hei. 11-142338 discloses a method by which the absorbance at the coloration part is measured without influence of outside light by using a light emitting diode as a light source.
However, in the conventional chromatography quantitative measuring apparatus, which has no problem with respect to immuno-chromatography for qualitative analysis, in the case of quantitative analysis, when, for example, a liquid sample including cellular components, such as blood, is to be analyzed, the viscosity of the liquid sample or the existence of cellular components generates partial clogging, resulting in non-uniform coloration at the base part of the immuno-chromatography test strip. Thus, as the concentration is obtained by the difference between the absorbance signal at the base part and that at the detection part, when an error is generated due to the non-uniform coloration at the base part according to the position where a beam is applied, a quantitative measurement is disturbed. Further, when a spectrophotometer which uses a lamp as a light source is used, it is difficult to reduce the size and cost of the apparatus.
Further, in the above-described conventional chromatography quantitative measuring apparatus, since the inspection target solution is slowly developed on the development layer 85, a value of a detection signal is gradually varied with time at the detection part 83 of the chromatography test strip 8. That is, in order to obtain a more stable measurement result, it is important to manage time to perform a measurement. In the conventional measurement using a spectrophotometer, there is no function of managing time, and as a result, an inspector has to manage time manually, which causes trouble in a measurement operation. Further, there is sometimes a test strip on which a normal measurement is disturbed according to the inspection target solution or a state of the chromatography test strip 8. In the conventional measurement using a spectrophotometer, there is no function of detecting the state of the inspection target solution or the chromatography test strip 8, and as a result, an inspector has to judge the state manually, which causes trouble in a measurement operation. Furthermore, since a marker reagent remains at the marker reagent hold part 82 of the chromatography test strip 8 even after its elution, influences of the residual marker reagent must be reduced in order to enhance the accuracy of a quantitative measurement. However, in the conventional measurement using a spectrophotometer, there is no function of recognizing the residual marker reagent, and as a result, an inspector has to recognize it manually, which causes trouble in a measurement operation.
Further, an immuno-chromatography test strip for a qualitative or semi-quantitative measurement is generally put in a hollow casing and discarded together with the casing when an inspection is ended. For example, in Japanese Published Patent Applications No. Hei. 1-503174 and No. Hei. 6-180320, methods are disclosed in which a casing 90 with an injection part 91 through which a liquid sample is applied to the immuno-chromatography test strip, and an aperture 92 for observing a coloration part are provided, and the degree of coloration is visually judged as an inspection result, as shown in FIG. 25(c). Further, in immuno-chromatography quantitative analysis for measuring the degree of coloration by a multi-purpose spectrophotometer, there is no problem in employing the casing when the frequency of measurements is low. However, when a quantitative measurement is performed frequently for the purpose of clinical examination or the like, there is a problem of the cost of the casing and a storage space to be secured. On the other hand, when the quantitative measurement is performed by solely employing the immuno-chromatography test strip without the casing, the test strip is put on a measurement table of the spectrophotometer directly, so that a sample adheres to a measuring apparatus. Furthermore, the test strip must be attached to the measuring apparatus precisely so that a beam is accurately applied to the base part and the detection part.
The present invention is made to solve the above-mentioned problems. Accordingly, an object of the present invention is to provide a chromatography quantitative measuring apparatus which makes highly accurate immuno-chromatography quantitative analysis possible and realizes a reduction in the size and cost of the apparatus, a chromatography quantitative measuring apparatus which improves operationality thereof, or a chromatography quantitative measuring apparatus which enhances the accuracy of a quantitative measurement.